1. Technical Field
The present invention relates to an illuminated switch device in which an operating body is inserted into a casing having a plurality of light sources provided therein such that it can move in the vertical direction and light components emitted from the light sources are individually incident on a plurality of illuminated regions that are provided on an upper plate of the operating body, and more particularly, to a technique capable of preventing the leakage of light.
2. Related Art
The general structure of this type of illuminated switch device will be described below. A casing with an open upper end is provided on a substrate, and a partition wall integrally formed with the casing is provided on the inner bottom of the casing. Light sources, such as LEDs, are provided in a plurality of regions of the substrate that are partitioned by the partition wall. In addition, a plurality of illuminated regions on which light components emitted from the light sources are individually incident are provided on the upper plate of an operating body, and an outer housing that extends downward from the upper plate is inserted into the casing so as to be movable in the vertical direction. In this way, the operating body can be pressed against the casing. Further, in the operating body, a light-shielding wall that divides a space surrounded by the outer housing into small spaces corresponding to the illuminated regions is provided on the rear surface of the upper plate, and a partition portion is formed in the casing by the light-shielding wall and the partition wall. Therefore, light emitted from the light source that is provided in one of the illuminated regions partitioned by the partition wall is prevented from reaching the other illuminated region. In addition, a switch element, such as a push switch, is provided on the substrate inside or outside the casing. When the operating body is pressed, the switch element is turned on.
In the illuminated switch device having the above-mentioned structure, guide rails and concave grooves are provided at proper positions of the outer housing of the operating body and the inner wall surface of the casing as guide mechanisms for smoothly moving the operating body in the vertical direction. A technique for slidably fitting the guide rails into the concave grooves has been proposed (for example, see JP-A-9-231855).
FIG. 7 is a plan view illustrating the related art, in which the upper plate of an operating body is omitted. In the illuminated switch device shown in FIG. 7, a first light source 31 and a second light source 32 are provided on a substrate 40 of a casing 30, and regions for the light sources 31 and 32 are partitioned by a partition wall 33 that is provided on the inner bottom of the casing 30. An open end 30a is provided at the top of the casing 30, and concave grooves 34 are provided at four positions in the inner wall surface of the casing 30 so as to extend in the vertical direction (the direction that is perpendicular to the plane of the drawing). An outer housing 35 of an operating body, which is pressed, has substantially the same outer shape as the open end 30a of the casing 30 in plan view. The outer housing 35 is inserted into the casing 30 so as to be movable in the vertical direction. Guide rails 36, which extend in the vertical direction, protrude from the outer housing 35 at positions corresponding to the concave grooves 34. The guide rails 36 are slidably fitted into the corresponding concave grooves 34. In addition, the operating body is provided with a light-shielding wall 37 that divides a space surrounded by the outer housing 35 into a first small space 38 and a second small space 39. The light-shielding wall 37 is provided immediately above the partition wall 33. One of the illuminated regions provided on the upper plate (not shown) of the operating body is opposite to the first light source 31 through the first small space 38, and the other illuminated region is opposite to the second light source 32 through the second small space 39. The first and second small spaces 38 and 39 are closed by the upper plate. Since the light-shielding wall 37 and the partition wall 33 form a partition portion in the casing 30, light emitted from the first light source 31 is shielded by the partition portion such that it does not enter the second small space 39. Similarly, light emitted from the second light source 32 is shielded by the partition portion such that it does not enter the first small space 38.
In the illuminated switch device having the above-mentioned structure, a predetermined gap C is ensured between the outer housing 35 of the operating body and the inner wall surface of the casing 30. However, since the guide rails 36 provided on the outer housing 35 of the operating body are slidably fitted into the concave grooves 34 provided in the casing 30, it is possible to move the guide rails 36 substantially in the vertical direction. In addition, since the guide rails 36 are provided at the edge of the outer housing 35 at four positions with a good balance, it is possible to prevent the outer housing 35 from being inclined. Therefore, it is possible to smoothly move the operating body in the vertical direction.
However, in the illuminated switch device according to the related art shown in FIG. 7, the course of light leaking from the light sources 31 and 32 to the gap C between the outer housing 35 of the operating body and the inner wall surface and the casing 30 is not particularly considered. Therefore, light leaking to the gap C is likely to reach the edge of the open end 30a through the upper parts of both ends of the partition wall 33 (both ends in the vertical direction in FIG. 7). For example, light is emitted to the illuminated region immediately above the first small space 38. Therefore, when only the first light source 31 is turned on, light emitted from the first light source 31 in the direction of an arrow A in FIG. 7 reaches portions B of the gap C through the upper parts of both ends of the partition wall 33 where the light-shielding wall 37 or the outer housing 35 is not provided. As a result, although the illuminated region immediately above the second small space 39 is not illuminated, light leaks from around the illuminated region. In particular, light leaks from the second small space in a dark place, which results in significant deterioration of lighting quality.